[Elecraft] VCO Relationship with 4 MHz Oscillator

[W3FPR - Don Wilhelm]

Mike and all,

An external 4 MHz oscillator does not work because there is no provision to 
inject an external oscillator into the MCU in place of the crystal 
oscillator.  It would require a hardware mod to use it.

Setting the reference oscillator accurately is not difficult - if you have a 
very accurate external counter, you can read the same frequency source with 
both the internal and external counter and simply match the interal counter 
reading.
The newer method of setting the reference now on the Elecraft webside 
(previously known as the 'N6KR method') is even more accurate because it 
automatically compensates for slight variations in the reference frequency 
required - a few folks have reported that the reference must be set a few 
cycles away from 4 MHz  for the most accurate results.

73,
Don W3FPR

----- Original Message ----- 
>
> Thanks for this explanation.  Is there an implication here that if you had 
> a
> more accurate external 4MHz source you could switch it in when you run CAL
> PLL to get a more accurate result in the look-up table?
>